Finding the Fourth Proportional to 1,560.39, 2,153.31 and 861.75

Step by Step Solution

1. Step 1: Write the proportion equation
   1,560.39 : 2,153.31 = 861.75 : x
2. Step 2: Convert to fraction form
   1,560.39/2,153.31 = 861.75/x
3. Step 3: Cross multiply
   1,560.39x = 2,153.31 × 861.75
4. Step 4: Simplify right side
   1,560.39x = 1,855,614.89
5. Step 5: Solve for x
   x = 1,855,614.89/1,560.39
6. Step 6: Final answer
   x = 1,189.20